How to Read an Indian Spectacle Prescription: SPH, CYL, AXIS, ADD & DV/NV Explained

A standard Indian ophthalmic prescription is structured as a grid with distinct medical columns:

• RE / OD (Right Eye / Oculus Dexter): Optical values for your right eye.
• LE / OS (Left Eye / Oculus Sinister): Optical values for your left eye.
• SPH (Sphere): Indicates the primary refractive correction for nearsightedness (Myopia, indicated by a Minus sign, e.g., -2.50 D) or farsightedness (Hyperopia, indicated by a Plus sign, e.g., +1.75 D).
• CYL (Cylinder): Indicates the power needed to correct Astigmatism—an uneven curvature of your cornea (shaped like a football rather than a basketball).
• AXIS (1° to 180°): The precise angular orientation of the astigmatic cylinder. A cylinder power must always have an axis.
• ADD (Near Addition): The additional magnifying plus power (typically +1.00 D to +2.75 D) required for reading and phone work in individuals over age 40 experiencing presbyopia.
• DV / NV: Distant Vision (Door ki nazar) and Near Vision (Paas ki nazar).

In India, ophthalmologists frequently write prescriptions in Plus Cylinder format, while optical surfacing laboratories use Minus Cylinder format. They represent the exact same lens power via optical transposition:

$$\text{New SPH} = \text{Old SPH} + \text{Old CYL} \quad | \quad \text{New CYL} = -(\text{Old CYL}) \quad | \quad \text{New Axis} = \text{Axis} \pm 90^\circ$$

For example: $+1.00\ \text{DS} / +1.00\ \text{DC} \times 90^\circ$ transposes into $+2.00\ \text{DS} / -1.00\ \text{DC} \times 180^\circ$. Both provide identical visual focus!

Patients often confuse prescription lens power (e.g., -2.00 D) with visual acuity (6/6). 6/6 (equivalent to 20/20 in feet) simply means that at 6 meters, you can read the standard letters that a normal healthy eye can see at 6 meters. Glasses are the optical tool that corrects your refractive error so your visual acuity reaches 6/6.